Air-cooled piston



Oct. 1, 1957 c, GATES 2,808,039

AIR-COOLED PISTON Filed Oct. 11 ,1955 5 Sheets-Sheet l ZNVENTOR idaies ATTORNEYS Oct. 1, 1957 A. c. GATES AIR-COOLED PISTON 5 Sheets-Sheet 2 Filed Oct. 11 ,1955

MN N Q I ATTORNEYS Oct. 1, 1957 A. c. GATES AIR-COOLED PISTON 3 Sheets-Sheet 3 Filed Oct. 11 ,1955

INVENTOR uia ales ATTORNEYS ed States Patent AIR-COOLED PISTON Alfred C. Gates, Corry, Pa., assignor to Ajax Iron Works, Corry, Pa.

The present invention relates to air-cooled pistons, and

more particularly to piston structures which utilize scavenging air for cooling the piston prior to delivery to the cylinder.

The primary object of the invention is to provide a jet air directing structure for moving cooling air against the base of a piston during the power stroke.

Another object of the invention is to provide in an aircooled piston structure of the class described, a heat conducting internal piston structure for radiating the heat from the piston to the air.

A further object of the invention is to provide in an air-cooled piston engine, means for compressing the cooling air and for directing it forcefully against the piston.

A still further object of the invention is to provide a structure of the class described which will be inexpensive to manufacture, non-complex in operation and simple to maintain.

Other objects and advantages will become apparent in the following specification when considered in the light of the attached drawings, in which:

Figure l is a central longitudinal cross-section of the invention shown partly broken away;

Figure 2 is a view similar to Figure 1, showing the piston at the opposite end of the cylinder;

Figure 3 is a transverse fragmentary cross-section taken along the line 33 of Figure 1, looking in the direction of the arrows;

Figure 4 is a transverse fragmentary cross-section taken along the line 44 of Figure 1, looking in the direction of the arrows;

Figure 5 is a fragmentary detail cross-section taken along the line 55 of Figure 4, looking in the direction of the arrows;

Figure 6 is an end view of the air piston; v

Figure 7 is an enlarged fragmentary detail cross-section similar to Figure 1, showing the valve structure, and

Figure 8 is a fragmentary transverse cross-section taken along the line 88 of Figure 7, looking in the direction of the arrows.

Referring now to the drawings in detail, wherein like reference numerals indicate like parts throughout the several figures, the reference numeral 10 indicates generally an engine block of the two-cycle variety. The engine block 10 includes a cylinder 11, a head 12 and conventional water-cooling jackets 13. The cylinder 11 is provided with an exhaust port 14, intake port 15, air and gas mixing manifold 16, scavenging chamber 17, and an engine bed 18, all constructed in. a conventional manner. A piston rod 19 extends axially through the cylinder 11 and is connected at one end to a crosshead (not shown) for delivering power to a crank shaft (also not shown).

A piston 20 is secured to the opposite end of the piston rod 19 and is adapted to reciprocate in the cylinder 11. Piston 20 is provided with sealing rings 21 engaging the cylinder 11. The piston 20 is recessed at 22 annularly with the recess 22 extending into the piston 20 from the same side of the piston 20 as the piston rod 19 extends.

2,808,039 Patented Oct. 1, 1957 A series of radially extending fins 23 connect the outer wall 24 of the piston to the central hub 25 thereof, radial fins 23 each being in a plane with the axis of the piston 20; A stuffing box 26 is mounted in the engine bed 18 by means of a stufling box support 27 which also closes the end of the engine bed 18. Packing 28 is positioned in the stufling box 26 and has the piston rod 19 extending therethrough. An air piston 29 is mounted to the stufling box 26 by means of a flanged base 30, the opposte end of the air piston 29 being provided with a circular head plate 31. A spider 32, having a multiplicity of arms 33, is integrally secured to the inner wall of the piston 20 at the outer ends of the arms 33. A spider hub 34 connects the inner ends of the arms 33 and engages over the piston rod 19, as illustrated in Figures 2 and 4.

A cup-shaped cylinder 35 is secured to the spider 32 by means of rivets 36 or the like. Cup 35 has a cylindrical wall 37 and an end wall 38, with the end wall 38 positioned against the spider 32 with the open end of the cylinder 35 facing the air piston 29. A series of air tubes 39 are secured to and extend through the end wall 38 of the cylinder 35 to permit air compressed in the cylinder 35 to be released therefrom. Reciprocation of the piston 20 in the cylinder 11 causes a reciprocation of the cylinder 35 about the head 31 of the air piston 29, creating a compressive air stream through the air tubes 39. The air passing through the air tubes 39 impinges on the piston 20 within the recess 22 surrounding the fins 23.

The cylinder 35 is smaller than the internal diameter of the lower end of the piston 20 to provide an annular air passage 40 therebetween. Air from the scavenging chamber 17 is drawn into the cylinder 11 by movement of the piston 20 toward the head 12, and upon movement of the piston 20 away from the head 12 air in the air cylinder 35 is compressed by the circular head plate 31 of the air piston 29 so as to force it toward the recess 22 and against the fins 23 and the piston 20, thus cooling the piston 20.

The gases are then forced through the annular air passage 4t intake ports 15, into the cylinder 11 on the opposite side of the piston 20. Compression of these gases by the piston 20 moving toward the head 12 prepares them for the explosion which follows in a conventional manner, driving the piston 20 away from the head 12.

The circular head plate 31 of the air piston 29 is provided with a multiplicity of apertures 41 extending with their axes parallel to each other and to the axis of the piston rod 19. A valve plate 42 is positioned on the circular head plate 31 between the plate 31 and the end wall 38 of the cylinder 35. The valve plate 42 is provided with a plurality of flexible radially extending valve fingers 43, with the outer end of each of the valve fingers 43 covering one of the apertures 41 so that a vacuum cannot form between the wall 38 and the head plate 31 as the cylinder 35 is moved away. On movement of the cylinder 35 away from the head plate 31, the flexible valve fingers 43 will move away from the apertures 41 permitting air to flow from the stufiing box 26 side of the head plate 31 into the cylinder 35.

In two-cycle gas engines of the type utilizing a separately partitioned scavenging chamber of the engine bed 18, in combination with the rod side of the piston to compress the scavenging air, the piston is cooled by its contact with a water-cooled cylinder which is often times insuflicient to adequately carry off the heat collected in the piston.

The instant invention contemplates the construction of the piston with radially extending cooling fins arranged in the rod side of the piston, in combination with an air by against the fins andbetween them establishing an air flow to additionally cool the piston. The air utilized for this purpose is the normal scavenging air directed to the cylinder in the normal manner. y

Having thus described the preferred embodiment of the invention, it should be understood that numerous modifications and structural adaptations may be resorted to without departing from the scope of the appended claims. y 7

What is claimed is:

1. A two-cycle engine comprising a cylinder, a piston reciprocably carried in, said cylinder, a boss formed in the center of said piston, said boss having a bore extend ing axially therethrough; a piston rod having one end thereof mounted in said bore, an outer wall on said piston extending parallel to said boss, and radial cooling fins,

extending between said boss and said outer wall.

2. A device as claimed in claim 1, wherein a stationary piston is mounted in said engine surrounding said piston rod and a cylinder is mounted on said reciprocating piston V to reciprocate therewith and cooperate with said stationary piston to compress air, and means are provided for directing said compressed air against said cooling fins.

3. A device as claimed in claim 2, wherein said cylinder mounted on said reciprocating piston is detachably secured to said reciprocating piston.

4. A device as claimed in claim 2, wherein said means for directing air includes a plurality of radially arranged parallel tubes communicating with Said moving cylinder and opening toward said cooling fins.

References Cited in the file of this patent UNITED STATES PATENTS 1,289,953 Suplee Dec. 31, 1918 1,628,652 Carlson May 17, 1927 1,688,403 Sperry Oct. 23, 1928 2,150,740 Hammersmith Mar. 14, 1939 FOREIGN PATENTS 504,105 Great Britain Apr. 19, 1939 

